Speedo Stopped Working

[amkothaw]

Hey Guys,

I have a 1990 Z32 NA. Yesterday, the speedo stopped working. I checked around online, and got a couple of answers but I just wanted to run it by here! So the speedo doesn't work and the cruise does not engage, but the odo and the trip meter are working. So let me know what you guys think it could be and what you think it may cost. I am new to Z cars and I love mine but I don't wanna get duped by a mechanic.

thanks


actually, the odo is not really working. its actually very very slow. i have driven about 30 miles so but its only moved about 5 miles.

[BigTDogg (MA)]

ODO could be a separate issue. They tend to get dirty and need a cleaning every 100k miles or so.

http://twinturbo.net/nissan/300zx/forum ... epair.html

http://www.angelfire.com/geek/vg30dett/ ... luster.htm

[amkothaw]

hey, just an update. A customer of my mechanic had a used speed sensor that he let us try out. Turns out that even with that one, my speedo is not working and also the odometer. I wanted to ask you guys if there could be anything else wrong and if you know how this whole thing is routed. Does the vss send the speed signal to the ECU and from there to the gauge cluster? Also, I remember reading somewhere (can't find the thread right now) that a faulty cruise control can make the speedometer stop working. Any ideas? She drives perfectly well, except a little tighter steering. Only becomes problematic when I am speeding up through the turn because the PS kicks in mid turn!

[Ace2cool]

Other way around. If the cruise control works, the gauge cluster is the culprit. That's where I would start. Get up to speed (judge >30mph) and try to engage the cruise control. If it doesn't do anything when you try to set the speed, it's the VSS. If it goes into cruise and maintains speed, it's the gauge cluster or wiring.

[amkothaw]

hey all,

thanks for all the help on this. I have a new development I would like to share. So I got my VSS replaced with another used one by the mechanic I use. I was still not getting a speed signal on the speedo. Now I have noticed that on some nights my speedo works. It is weird because it only seems to work at night! Then steering comes alive and it is always a let down when I turn the car on the following day and the speedo doesn't work anymore. I don't know whats going on really. Any helpful hints?

Thanks again.

Also, when the speedo is not working, the cruise does not engage.

[NolimitZ32]

I'm going to guess a loose ground in the VSS circuit, tht would explain why it is intermittent.

[amkothaw]

Hey Nolimit,
Nice to talk with a Houston Z owner! Thanks for your input. I will look into that. Do you know where the VSS circuit ground is? Sorry for the noobish question.
Thanks again.